Hello Friend, Good that you are seeking a help here. Anxiety could be the reason for your loss of concentration and lack of energy. It needs detailed assessment to recommend a solution.
You need proper sleep and little changes in lifestyle to control your mind.
Next Steps
Feel free to reach out to me online through Practo for further detailed evaluation and suitable solutions that you can follow practically to overcome this problem. Be positive. You will be alright soon.
Health Tips
Have a cup of warm milk before sleep. Finish your dinner min 3hrs before sleep. Create a timing hygiene for use of mobile and social media.